Wireless two way transmission between center and user stations via a relay

ABSTRACT

The present invention is directed to a communication system which can be utilized to complement an existing cable television system in which a central office transmits signals along a coaxial cable to a user unit through a tap. The communication system features a central transmitting/receiving unit for wirelessly transmitting first signals generated at the central office and for receiving second signals. A first response unit which may be connected to the tap will receive the first signals wirelessly transmitted from the central transmitting/receiving unit, and will generate and wirelessly transmit the second signals to be received by the central transmitting/receiving unit. A further second response unit may be connected to the user unit, and the second response unit may generate a third signal to be wirelessly received by the first response. The third signal may be used to control the tap connected to the first response unit. Further, a relay unit may be provided to facilitate transmission between the first and second response units in the central transmitting/receiving unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a two-way communication systemwhich may find particular application as a complement to existing cabletelevision communication systems.

2. Discussion of the Background

Cable television systems are conventional and well known, and aschematic diagram of a conventional cable television system is shown inFIG. 1. As is shown in FIG. 1, a conventional cable television systemfeatures a cable control station 5 which has a coaxial cable outputtherefrom. The coaxial cable carries television and control signals.Along the transmission path, amplifier stages 10(n) are utilized toamplify the transmitted signals to ensure that the signals transmittedalong the coaxial cable are at an appropriate amplitude. Also, standbybatteries 70 may be connected along the transmission path to provideback-up power in the event of a power failure. Connected to theamplifier stages 10(n) are various taps 15(n), and output of these taps15(n) are the coaxial cables which are input to a user 20(n), e.g., thehome of the customer. These taps 15 are typically formed on a utilitypole, in an underground pedestal or, in a case of an apartment building,within a security closet.

Conventional cable systems suffer from several significant shortcomingsand drawbacks.

One significant drawback is that the theft of the cable signalstransmitted along the coaxial cable is very common. One type of cabletheft is an unauthorized user simply accessing the cable tap 15,connecting an unauthorized cable thereto, and receiving the signals fromthe cable. Such a theft however typically does not allow the cable thiefto access premium channels or pay-per-view channels. A further type oftheft is if a user further has a decoder or descrambler to gain accessto the scrambled premium or pay-per-view channels.

Cable systems have developed various techniques to combat such cabletheft. To prevent unauthorized access of a tap, a locking terminator maybe placed on the tap itself. One way of preventing viewers fromreceiving the premium or pay-per-view channels is that an extraneoussignal, which may typically be 2.5 MHz, is inserted above a normalvisual carrier. This causes the television at the user 20 to think it isreceiving a strong signal, and the television then automatically adjustsfor this gain, which results in overriding or hiding the real cablesignal. To overcome these situations, a trap must be placed at the tap15 to remove this extraneous signal, and this thereby allows anyauthorized channel to be viewed by the user 20.

Such a security system to ensure that users 20 only receive cable ifthey have paid for the service and receive the channels they pay for hasa significant drawback in that any time a user 20 changes their serviceand either is entitled to receive additional channels or cancels certainchannels, the cable system must dispatch a technician to the appropriatetap 15 to change the configuration of the traps therein. This is acostly and time consuming operation and a significant drawback in such asystem.

Furthermore, any time a user 20 cancels a cable service, a technicianmust also physically go to the appropriate tap 15, which may typicallybe on a utility pole, disconnect the cable and, possibly place aphysical lock on the tap 15. Such an operation is again costly and timeconsuming for the cable systems.

Another common situation of cable theft is the inadvertent theft ofservices. In such a situation, a cable user 20 inadvertently receiveschannels which the user 20 is not paying for and authorized to receive.This situation often occurs when a cable technician fails to disconnectthe cable or install the appropriate traps in the taps 15 to blockchannels from reaching a user. Such a type of inadvertent cable theft isvery difficult to detect in conventional cable systems as they can onlybe detected by a visual inspection of the taps 15.

A further problem in conventional cable systems is effectivelyaddressing a cable-out situation in which for some reason cable signalsare not properly transmitted to certain users. Such a cable-outsituation may occur if a cable gets cut, if there is a power loss, etc.The conventional way of detecting such a cable-out situation is for acable system to await complaints from the users, and then to send atechnician to determine the cause of the cable-out.

A cable-out can be caused by a loss of electrical power. In such asituation, a user 20 that is experiencing a cable-out may not beexperiencing a similar power loss in their home as their home may beserved by a different utility transformer than the cable. It is commonfor a cable system to have standby batteries 70 to accommodate for aloss of power cable-out. The condition of the standby batteries 70 willdetermine if an affected area experiences a cable-out as a result of thepower loss. If the batteries are at full power, then the batteries maybe able to provide power during a power loss.

To test the status of such standby batteries 70, cable systems mustperiodically send a technician out to the battery sites to physicallytest each battery unit. Such a procedure of determining the status ofthe standby batteries 70 is very costly and time consuming.

Also, and with reference to FIG. 1 of the present specification, severalamplifier stages 10(n) are formed along the cable transmission path toensure that the transmission signal provided to the users 20 is at anappropriate level. These amplifiers may include manual trunk amplifiers,automatic trunk amplifiers, trunk/bridging amplifiers, line extendingamplifiers, and may also include AC power supply units or power inserts.If one of these amplifiers 10 malfunctions, a cable-out may occur to auser. In such a situation, to determine the cause of the cable-out, thecable system will have to send a technician out to check all possiblecauses of the cable-out, and to determine whether the amplifier stages10 have any malfunctions. Such a procedure of determining the status ofthe amplifiers 10 is very time consuming and costly to the cable system.

Another problem with cable systems is that cable systems are required bythe Federal Communications Commission to test for signal leakage orradiation. Conventionally, this test is performed by sending atechnician out into the cable franchise area with a detector fordetecting for such signal leakage or radiation. Again, such a testingoperation which requires a time consuming operation by a technician isvery inefficient.

One common and significant inefficiency in the operation of a standardcable system such as is shown in FIG. 1 is the necessity for a manualcontact or disconnect of the service at the tap 15(n). That is, inconventional cable systems, each time a user 20 requests a connect ordisconnect, the cable system must dispatch a technician to theappropriate tap 15(n) to connect or disconnect the service. This is acostly and time consuming operation and a significant drawback in such asystem.

There has also been an increase in the demand for two-way communicationbetween a cable user and the cable control system. For example, suchtwo-way communication can be used to allow the cable user 20 to orderpay-per-view programming being offered by the cable system. An effectivesupply of such programming is important for a cable system as it is asignificant source of revenue for the cable system. At the present time,systems for allowing the user to control such pay-per-view operationseither require the user to have a specialized cable box and the cablesystem must be designed for two-way communication or the user must callthe cable system to order special programming.

The two-way communication system requires very complicated circuitry inallowing two-way communication along the cable, and is particularlydifficult to implement in cable systems which have already beeninstalled and designed without such a feature. The user call system iscumbersome for the user and requires extensive communication equipmenthooked to the phone lines.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a novelcommunication system which can be used in complement with a cabletelevision system which overcomes the problems and drawbacks inconventional cable systems.

A further more specific object of the present invention is to provide anovel communication system for use with a cable television system whichallows more efficient control of the cable signal passing through a tapto a user.

A further more specific object of the present invention is to provide anovel communication system for use with a cable television system whichallows more efficient monitoring of cable theft.

A further more specific object of the present invention is to provide anovel communication system for use with a cable television system whichallows more efficient monitoring of cable-outs.

A further more specific object of the present invention is to provide anovel communication system for use with a cable television system whichallows efficient testing of a signal leakage or radiation.

A further more specific object of the present invention is to provide anovel communication system for use with a cable television system whichallows efficient two-way communication between a user and a cablecontrol station, and particularly which allows easy two-waycommunication in a system which is easy to retrofit on existing cablesystems.

The objectives of the present invention are achieved by a novelcommunication system for use with a cable television system in which acentral office transmits signals along a coaxial cable to a user unitthrough a tap. According to the communication system of the presentinvention, a central transmitting/receiving unit wirelessly transmitsfirst signals generated at the central office, and the centraltransmitting/receiving unit also receives second signals. A firstresponse unit receives the first signals wirelessly transmitted from thecentral transmitting/receiving unit, and generates and wirelesslytransmits the second signals to be received by the centraltransmitting/receiving unit. The first response unit may be connected tothe tap through which the user unit receives the cable signals.

As a further feature of the present invention, a second response unitmay be connected to the cable box of the user unit, and the secondresponse unit may generate a third signal to be wirelessly received bythe first response unit or central transmitting/receiving unit. Thisallows effective two-way communication between a user unit and a cablecontrol station.

The system of the present invention also allows effective monitoring ofthe tap to determine cable theft and a cable-out, allows an effectivemonitoring of a signal leakage or radiation, and permits easy andefficient control by the cable user.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 represents a conventional cable system;

FIG. 2 represents an overview of the communication system of the presentinvention;

FIG. 3 shows the details of a cell transmitter/receiver shown in FIG. 2;

FIG. 4 shows the details of a cell relay shown in FIG. 2;

FIG. 5 shows the details of a micro-response transmitting unit (M-RTU)shown in FIG. 2; and

FIG. 6 shows the details of a response transmitting unit (RTU) shown inFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly to FIG. 2 thereof, there is shown an overview of thecommunication system of the present invention.

The present invention is essentially directed to a wireless controlsystem which can be retrofitted onto existing systems and provide acontrol or a monitoring of the existing systems. One preferredembodiment of the system of the present invention is as a complement toan existing cable television system, and this preferred embodiment isdiscussed in detail below. However, it is to be understood that thesystem of the present invention can find application in other types ofsystems which would benefit from a wireless monitoring or control.

As is shown in FIG. 2, the communication system of the present inventionmay operate in conjunction with the conventional cable transmissionsystem. According to the present invention, a centraltransmitter/receiver unit 85 is connected to the cable control station5. Furthermore, connected to most of the amplifiers 10, standbybatteries 70, cell relay 80 and taps 15 is a respective micro-responsetransmitting unit (M-RTU) 95(n). Connected to each of the user units 20is a response transmitting unit (RTU) 90(n).

According to the present invention, the cable control station 5 cangenerate various signals which can be wirelessly transmitted by thecentral transmitter/receiver 85. The signals transmitted by the centraltransmitter/receiver 85 are then received by the micro-responsetransmitting units 95. As the micro-response transmitting units 95 areconnected to the amplifiers 10, standby batteries 70, cell relay 80 andtaps 15, these micro-response transmitting units can generateinformation as to the operation of the amplifiers 10, standby batteries70, cell relay 80 and taps 15, and can also control the amplifiers 10,standby batteries 70, cell relay 80 and taps 15.

FIG. 3 shows a specific configuration of the centraltransmitter/receiver unit 85. As is shown in FIG. 3, the centraltransmitter/receiver unit 85 features a digital data computing device340. This digital data computing device 340 may be formed by ahigher-power computing device such as a Sun Microsystems workstation ora high-end personal computer such as a Pentium or 486 machine. Thisdigital data computing device 340 is connected to the cable controlstation 5 and receives signals from the cable control station 5 andprovides signals to the cable control station 5.

The signals to be transmitted by the central transmitter/receiver unit85 are output from the digital data computing device 340 to atransmitter 330. The transmitter 330 includes a channel encoder 332 anda digital modulator 334. According to the present invention, differentsignals can be sent to different receiving units by an appropriateencoding. In the present invention each M-RTU 95(n) can have anindividual address. In the digital data computing device 340, a specificaddress of selected M-RTUs 95 can be designated if only a selectednumber of the M-RTUs 95 are to be addressed. The channel encoder 332 isprovided to insert error detection and correction information into thetransmission data stream, for example by a known 1/2 rate convolutionencoding algorithm such as implemented in circuits by Qualcomm orStanford Telecom.

As an example of the operation of the present invention, one signalwhich may be generated by the cable control station 5 is a pollingsignal which polls whether the amplifier units 10, standby batteries 70,taps 15 or cell relay 80 are operating properly. In this situation onlythe M-RTUs 95(1) and 95(3) which are connected to the amplifiers 10 needto be addressed if the operability of amplifiers 10 is being polled, orM-RTU 95(5) if the cell relay is being polled, or M-RTU 95(6) if thestandby batteries 70 are being polled. In the digital data computingdevice 340, a code signal can be provided which is unique to only theM-RTUs 95(1) and 95(3) connected to the amplifiers 10(1) and 10(3), sothat only these designated M-RTUs 95(1) and 95(3) act on the amplifierpolling signals generated by the cable station 5.

The channel encoded signals are then modulated in digital modulator 334and are then provided to transmit/receive switch 310, which may be anelectronic switch or coaxial relay. Transmit/receive switch 310 controlswhether the central transmitter/receiver unit 85 is operating in atransmission mode or a reception mode. The signals are then radiated byantenna 300, which may be a conventional antenna such as manufactured byDecibel Products or Scala Electronics.

Antenna 300 also receives signals generated from the M-RTUs 95 and theRTUs 90. These signals are received in receiver 320 and are demodulatedin digital demodulator 324 and decoded in digital data computing device340. Channel decoder 332 is provided to use the error detection andcorrection information in the decoding to increase data integrity. Thereceived signals after error detection and correction are then suppliedto the digital data computing device 340, and are then provided to thecable control station 5.

As noted above, typical types of signals generated by the centraltransmitter/receiver unit 85 are polling signals. A polling signal is asignal which can poll a particular unit to determine its operationalstatus. As discussed above, each M-RTU 95 and RTU 90 may have a uniqueaddress. As a result, in the present invention each polling signal maybe specifically encoded in digital data computing device 340 to bedirected to particular M-RTUs 95 or RTUs 90. As each of the pollingsignals is transmitted, each respective M-RTU 95 and RTU 90 willrecognize its unique address identification signal in the pollingsignal, and process only the polling signals intended for the particularrespective M-RTUs 95 and RTUs 90.

After each particular M-RTU 95 and RTU 90 receives its respectivepolling signal, each M-RTU 95 and RTU 90 can respond to the pollingsignal by generating response signals. These response signals arereceived by antenna 300 of the central transmitter/receiver 85 and areprovided to the cable control station 5 through receiver 320 and digitaldata computing device 340. These response polling signals may indicatewhether the devices to which the M-RTUs 95 or RTUs 90 are connected arefunctioning.

As discussed above as a specific example, the system of the presentinvention may periodically generate polling signals to determine whetherthe amplifiers 10, standby batteries 70 or cell relays 80 are operatingproperly. In this situation, the system of the present inventiongenerates specific polling signals for each specific M-RTU 95(1) and95(3) connected to an amplifier 10. When each of the M-RTUs 95(1) and95(3) connected to the amplifier 10 receives such polling signals, eachof the M-RTUs 95(1) and 95(3) determines whether the amplifier 10(1) and10(3) connected thereto is properly functioning. Each M-RTU 95(1) and95(3) then provides a unique response signal based on whether thespecific amplifier 10(1) and 10(3) connected thereto is properlyfunctioning. This response signal is then received by the centraltransmitter receiver unit 85 to provide the information as to theoperation of the amplifier units 10 to the cable control station 5.

Another type of signal which can be transmitted by the centraltransmitter/receiver unit 85 is an actual control signal which cancontrol an action of the taps connected to the M-RTUs 95 and RTUs 90.

For example, if a user 20 changes his/her level of cable service, e.g.to receive an extra premium or pay channel, the system of the presentinvention allows this change in service to be implemented remotely, i.e.without requiring a cable technician to physically change a cableconnection at the appropriate tap 15. This operation of the presentinvention works as follows. Assume that the user 20(1) has changedhis/her cable subscription package to receive an extra pay channel. Thecable control station 5 of the present invention then generates a signalwhich is provided to central transmitter/receiver unit 85. This signalwill specifically address the M-RTU 95(4) which is connected to the tap15(2), which in turn controls the signals provided to user 20(1). Thisspecific signal generated by the central transmitter/receiver unit 85controls the tap 15(2) to allow the extra pay channel to be transmittedto the user 20(1). In this operation of the present invention, the tap15(2) can be controlled, to operate as essentially a smart tap device,and this allows the cable system to remotely control the contents of thecable signal supplied to the user 20(1).

In this way, in the present invention the central transmitter/receiver85 can generate control signals which can open or close a signal path orchannel that a user 20 ultimately receives. Other types of signals whichcan be transmitted by central transmitter/receiver unit 85 are otherpolling signals, a signal which authorizes the M-RTUs 95 to conduct asignal strength test and report the results thereof, authorizing theM-RTUs 95 to automatically broadcast a signal indicating that a cablesignal has dropped to levels below a predetermined threshold, or anyother actions which may be required by the cable operation.

FIG. 4 shows the details of a cell relay 80, which is an optionalelement in the present invention. The function of the cell relay 80 isto receive signals from the individual M-RTUs 95 and RTUs 90, and torelay such signals to the central transmitter/receiver unit 85. The cellrelay 80 can be connected to the central transmitter/receiver 85 eitherby wire or by a wireless communication. The use of cell relay 80 allowsthe M-RTUs 95 and RTUs 90 to be of a lower power than would otherwise benecessary if the M-RTUs 95 or RTUs 90 directly communicated with thecentral transmitter/receiver 85. The distance between the M-RTUs 95 andRTU units 90 to the cell relay 80 is generally much less than thedistance from the M-RTUs 95 and RTUs 90 to the cell transmitter/receiver85.

As is shown in FIG. 4, the cell relay 80 has a similar construction tothe cell transmitter/receiver 85 in that the cell relay 80 features atransmitter 430 which includes a channel encoder 432 and digitalmodulator 434, a transmit/receive switch 410 and an antenna 400. On thereception side a receiver 420 includes a channel decoder 422 and adigital demodulator 424. The data transmitted and received also passesthrough a digital data computing device 440. This cell relay 80 operatesessentially as a conduit for information on and its main objective is toensure that the signals received are equivalent to the signalstransmitted in content. In the present invention several cell relayunits 80 may be dispersed throughout the cable franchise area.

The specifics of the M-RTUs 95 are shown in FIG. 5 of the presentspecification. Each of these M-RTU 95 features a transmitter 530 whichincludes a channel encoder 532 and a digital modulator 534, a receiver520 which includes a channel decoder coder 522 and a digital demodulator524, a transmitter/receive switch 510 and an antenna 500, similarly asdiscussed above with respect to the central transmitter/receiver 85 andcell relay 80. Furthermore, a digital data computing device 540 providesthe transmission signals and receives the reception signals, whichdevice may be a lower-power computing device such as a 4 bit or 8 bitmicroprocessor controller circuit card. These noted elements in theM-RTU unit 95 having similar operations as discussed above in that theseelements transmit and receive data and can encode the data to bereceived by only specific M-RTUs 95.

As shown in FIG. 5, also connected to the digital data computing devicesis an expansion port 595, a cable service on/off switch 560, achannel-specific interference generator or channel-specific trap 570, acable signal presence/strength sensor 580 and a cable leakage receiver590.

The expansion port 595 is essentially a port which can allow futureexpansion of the M-RTU 95. The cable service on/off switch 560 is acontrol device which can completely deactivate cable service. Thisswitch 560 can be used, for example, if a user 20 cancels a cablesubscription, then switch 560 can completely shut off cable service tothe designated user 20.

Channel-specific interference generator or channel-specific trap 570 isused to control the level of service to the user 20. Cable systems willhave different levels of service, for example, basic service, premiumservice and various premium channels. The channel-specific interferencegenerator or channel-specific trap 570 controls which channels areactually fed to a user 20 based on the level of service which the user20 has paid for. In this way, the M-RTU 95 can control the signalsprovided to the user 20.

Cable signal presence/strength sensor 580 monitors the amplitude of thecable signal provided to the user 20. The cable signal presence/strengthsensor 580 can be activated either by a polling signal transmitted bythe central transmitter/receiver unit 85 or can continuously monitor thecable signal presence/strength, and automatically activate the M-RTU 95to output an indication signal if the cable signal amplitude falls belowa predetermined level. It is also possible in the present invention tonot attach M-RTUs 95 to the amplifiers 10. In this situation, the outputof the cable signal presence/strength sensor 580 will provide an insightas to whether an amplifier 10 is malfunctioning.

The cable leakage receiver 590 can be used to continuously, or by apolling signal generated by central transmitter/receiver 85, monitorsignal leakage or radiation, such as required by the FCC. As the M-RTUs95 may typically be mounted on an auxiliary pole on which the tap 15 ismounted, and as these M-RTUs 95 may be provided throughout the cableservice area, the cable leakage receiver 590 will provide a goodindication of signal leakage or radiation.

The M-RTU device as shown in FIG. 5 is the device which will betypically connected to the taps 15. If a M-RTU device as is connected toan amplifier 10, standby batteries 70 or cell relay 80, such a devicewould not require the cable service on/off switch 560 or thechannel-specific interference generator or channel-specific trap 570. Inthis situation, the M-RTUs 95 connected to the amplifiers 10, standbybatteries 70 or cell relay 80 may only feature the expansion ports 595,the cable signal presence/strength sensor 580 and the cable leakagereceiver 590 and other specific circuitry to test amplifiers 10, standbybatteries 70 or cell relay 80.

FIG. 6 shows the details of the response transmitting units RTU 90. Theresponse transmitting units 90 feature transmitter 630 which includes achannel decoder 632 and a digital modulator 634, a transmitter/receiveswitch 610, an antenna 600, and receiver 620 which includes a channeldecoder 622 and a digital demodulator 624, similarly as discussed abovewith respect to the central transmitter/receiver unit 85, cell relay 80and M-RTUs 95. Further, the signals transmitted and received by the RTUs90 are input into a digital data computing device 640, which in turn isconnected to a user input device 650. This user input device 650 may beany type of input device such as a remote control keypad.

The use of the RTUs 90 provides each individual cable user 20 with aform of direct control over the cable service for each individual user20. The RTUs 90 allow information input from the user 20 via the userinput device 650 to be transmitted to the M-RTUs 95, to the central cellrelay 80 or to the central transmitter/receiver 85.

As one example of the operation of the RTUs 90, these RTUs 90 can beused by each individual user 20 to select a pay-per-view program in thefollowing manner. If a pay-per-view program is available, and if a user20 specifically desires to purchase such a pay-per-view program, theuser 20 will activate the user input device 650 in the RTU 90, whichtypically will be connected, either by wire or wirelessly, to the cablebox inside the user's home. The digital data computing device 640 willthen interpret this input as an indication that the user 20 wishes topurchase a specific pay-per-view program, and digital data computingdevice 640 generates a control signal based on this input.

This control signal is then encoded in channel encoder 632, and thesignal is then modulated in digital modulator 634 and then radiated byantenna 600. As this signal is a request for the user 20 to receive apay-per-view program, the signal radiated by antenna 600 will bereceived by the M-RTU 95 which is connected to the tap 15 which suppliesthe cable signal to the individual user 20.

With reference to FIG. 2 of the present specification as an example, ifuser 20(1) selects a particular pay-per-view program, user 20(1)provides such an input on a user input pad 650 in the RTU 90(1). The RTU90(1) then transmits a signal to the M-RTU 95(4), which in turn controlsthe tap 15(2) which supplies the cable signal to the user 20(1). Whenthe M-RTU 95(4) receives this request from the user 20(1), thechannel-specific interference generator or channel-specific trap 570formed in the M-RTU 95(4) controls the tap 15(2) to allow thespecifically selected pay-per-view program to be supplied to the user20(1).

Further, the M-RTU 95(4) also transmits a confirmation signal to thecell relay 80 which indicates that the user 20(1) has a selected theparticular pay-per-view program. This signal is then relayed to thecentral transmitter/receiver 85 and is then provided to the cablecontrol station 5. This confirmation signal which confirms the operationof the M-RTU 95(4) is supplied to the cable control station 5 so thatthe cable control station 5 can have an accurate and automaticaccounting of the pay-per-view selection of the user 20(1). In thisoperation of the present invention, the user 20(1) can individuallycontrol the pay-per-view selection, and the cable control station 5 willhave an accurate accounting thereof so that the user 20(1) can beappropriately billed.

The RTUs 90 can also receive signals from the centraltransmitter/receiver 85 or M-RTU 95(4), which signals may, as anexample, poll whether the RTUs 90 are operating properly. Further,responses to these polling signals in the RTUs 90 can then be directlytransmitted to the cell relay 80 or central transmitter/receiver 85,i.e., responses to such polling signals need not be transmitted to theM-RTUs 95.

As a further possibility of the operation of the RTUs 90, these RTUs 90can be used to poll a user. For example, the cable control station 5 maysend a polling signal to each of the users 20. Each of the users 20 canthen respond to this polling signal by inputting a specific data intouser input device 650. This data will then be transmitted back to thecable control station 5 through the cell relay 80 and centraltransmitter/receiver 85. In this situation the RTUs 90 will directlycommunicate with the cell relay 80 or central transmitter/receiver 85and again bypass the M-RTUs 95.

The system of the present invention can also be used to accuratelymonitor which programs a household is watching. It is a concern oftelevision programmers to have an accurate indication of whichprogramming a user is watching. This is conventionally done by pollingservices in which a user must keep a written log of the programming theywatch. By the use of the present invention, the RTUs 90 through thedigital data computing device 640 can keep an accounting of whichchannel a user is watching, and this information can then beautomatically transmitted back to the cable control station 5. With suchan operation, a very accurate record of a user's viewing habits can beobtained which does not rely on the user to make any efforts.

Clearly, other possibilities of the system of the present invention arealso possible. The system of the present invention has been described atthis time in a particular environment of a cable television system.However, the system of the present invention can find other applicationsin other environments.

As an example, the system of the present invention could also be used tomonitor power use. At this time power usage by homes and businesses ismeasured through meters which must be manually read by a technician fromthe power company. The system of the present invention could clearlyfind application in that a modified micro-response transmitting unit ofthe present invention could be attached to such power meters. In thissituation, in response to periodic polling signals the micro-responsetransmitting units could provide a central control station with anindication of the power usage. In such a situation the micro-responsetransmitter units could also alert a central control station as to amalfunction in a power meter.

The present invention can also be used in a demand side managementsystem for electrical and gas utility plants, as it would eliminate theuse of a dedicated telephone line therefore.

The present invention can also find particular use in monitored homesecurity systems, which presently are dependent on hard wire telephonesystems.

Specifically, current electronic home security systems are commonlyfound to be of many and varied types. Such systems range from verysimple devices attached to doors which sound an alarm when the door ismoved or shaken, to elaborate self-contained video systems, inclusive ofon-premise security guards. Of all these systems, the two most generallyused are on-premise alarm only systems or central station monitoringsystems.

In the case of an on-premise alarm only system, the doors, windows andother means of ingress and egress of the house are wired with electricalcontacts. When the circuit of one or all of these contacts is broken anon-premise alarm sounds. This alarm will alert neighbors in theimmediate area of a break-in. A central station monitoring system issimilarly wired. However, in addition to the on-premise alarm, a centralstation is linked by hardware telephone lines and a digital dialer. Thiscentral station receives a signal that an electrical circuit in acontact at a particular house has been broken. With the use of thiscentral station monitoring system, central station personnel can takeimmediate procedural action to alert proper authorities of a break-in.

The drawbacks with such conventional systems is that if the systemsthemselves have any malfunctioning elements, the malfunction of theseelements is not brought to anyone's attention. The present invention canovercome such drawbacks by setting forth a two-way wireless link betweena home and a central station. The wireless nature of the system of thepresent invention provides additional security in that there is no wirethat can be cut by a perpetrator. The present invention may specificallyutilize a modified form of an M-RTU as discussed above in theenvironment of the cable television system. The M-RTU used in the homesecurity device will be connected to the home security device todetermine its operation and functionality. Further, in the presentinvention the M-RTU will be continuously or systematically polled fordiagnostic testing to determine whether any element in the home securitysystem is not operating properly. This provides a significant advantageover existing systems which have no way of automatically detecting amalfunction.

In addition to normal security, the use of a M-RTU as in the presentinvention provides an ability to wirelessly link a home to a centralstation for emergencies such as regarding air quality, i.e. carbonmonoxide or other household contaminants, to link the system to awireless hand-held ingress and egress control and to link the homesecurity system to the local cable CATV system for on-screen reportingof an internal home status and external neighborhood watch and alertprograms. Further, the system of the present invention can also be usedfor fire and medical alert situations.

The system of the present invention may have a configuration in which aM-RTU is installed in the eaves of a house or in another securelocation. This M-RTU is connected to the home security system to monitorand control all contacts on the windows, doors and other ingress andegress portals of the house. The control link can be deployed wirelesslyor by an internal home hardwired network. Communication signals arereceived at the M-RTU from a central transmitter/receiver unit such asdisclosed in FIG. 2 with respect to the cable television environment ofthe present invention. The M-RTU may transmit, in response to pollingsignals or periodically self-generated signals, signals from the home tothe central transmitter/receiver. These signals contain specificmessages, such as a diagnostic of the operation of the home securitysystem, which are then transmitted to a central control station, andthus has a similar operation as discussed above with respect to thesystem disclosed in FIG. 2 of the present invention.

The present invention can also find particular use in inventory controlsystems such as for a vending machine industry as it can provide a lowcost method of reporting inventory levels of vending machines withoutthe need for an expensive hardwired link or without the need for visualinspection.

The present invention can also find particular application inenvironmental protection monitoring systems because the M-RTUs of thepresent invention can be economically placed within an extensivegeographical grid and can be attached to existing sensors which reportlevels of pollution via radio frequency.

Obviously, numerous additional modifications and variations of thepresent invention are possible in light of the above teachings. It istherefore to be understood that within the scope of the appended claims,the present invention may be practiced otherwise than as specificallydescribed herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A communication system for a cable televisionsystem in which a central location transmits signals along a coaxialcable to a user unit through a tap, comprising:a centraltransmitting/receiving unit for wirelessly transmitting a first signalgenerated at the central location and for receiving a second signal; afirst response unit for receiving the first signal wirelesslytransmitted from the central transmitting/receiving unit and forgenerating and wirelessly transmitting the second signal to be receivedby the central transmitting/receiving unit; a second response unitconnected to the tap, and wherein the second response unit generates athird signal; wherein the first response unit is connected to the tapand received the third signal, and wherein the third signal comprisescommand signals to control an operation of the tap connected to thefirst response unit, and the second signal includes an indication of thecommand signals of the third signal.
 2. A communication system for acable television system in which a central location transmits signalsalong a coaxial cable to a user unit through a tap, comprising:a centraltransmitting/receiving unit for wirelessly transmitting a first signalgenerated at the central location and for receiving a second signal; afirst response unit for receiving the first signal wirelesslytransmitted from the central transmitting/receiving unit and forgenerating and wirelessly transmitting the second signal to be receivedby the central transmitting/receiving unit; wherein the first responseunit is connected to an amplifier along the coaxial cable, and whereinthe first signal comprises a polling signal for polling an operation ofthe amplifier connected to the first response unit, and the secondsignal comprises response signals in response to the polling signal. 3.A communication system for a cable television system in which a centrallocation transmits signals along a coaxial cable to a user unit througha tap, comprising:a central transmitting/receiving unit for wirelesslytransmitting a first signal generated at the central location and forreceiving a second signal; a first response unit for receiving the firstsignal wirelessly transmitted from the central transmitting/receivingunit and for generating and wirelessly transmitting the second signal tobe received by the central transmitting/receiving unit; a secondresponse unit connected to the user unit, and wherein the secondresponse unit generates a third signal; wherein the first response unitis connected to the tap and comprises a controller for controlling anoperation of the tap based on the first and third signals.
 4. Thecommunication system according to claim 3, wherein the controllercomprises a cable service on/off switch for controlling a supply of thecable signals to the user based on the first signal generated by thecentral transmitter/receiver unit.
 5. The communication system accordingto claim 3, wherein the controller comprises a channel specificinterference generator or channel-specific trap to control channelssupplied to the user based on the first or third signals.
 6. Thecommunication system according to claim 4, wherein the controllercomprises a channel specific interference generator or channel-specifictrap to control channels supplied to the user based on the first orthird signals.
 7. The communication system according to claim 3, whereinthe controller comprises a cable signal presence/strength sensor fordetecting a presence and strength of the cable signals, and forgenerating the second signal in response an output of the cable signalpresence/strength sensor.
 8. The communication system according to claim6, wherein the controller comprises a cable signal presence/strengthsensor for detecting a presence and strength of the cable signals, andfor generating the second signal in response an output of the cablesignal presence/strength sensor.
 9. The communication system accordingto claim 3, wherein the controller comprises a cable leakage receiverfor detecting a radiation leakage of the cable signals, and forgenerating the second signal in response to an output of the cableleakage receiver.
 10. The communication system according to claim 8,wherein the controller comprises a cable leakage receiver for detectinga radiation leakage of the cable signals, and for generating the secondsignal in response to an output of the cable leakage receiver.
 11. Amicro-response unit to be connected to a tap in a cable televisioncommunication system providing cable signals to a user, comprising:atransmitter for generating and wirelessly transmitting a first signalindicating a status of the tap; a receiver for wirelessly receiving asecond signal; a controller for controlling an operation of the tapbased on the received second signal; wherein the controller comprises acable signal presence/strength sensor for detecting a presence andstrength of the cable signals, and for generating the first signal inresponse to an output of the cable signal presence/strength sensor. 12.The communication system according to claim 11, wherein the controllerfurther comprises a cable leakage receiver for detecting a radiationleakage of the cable signals, and for generating the first signal inresponse to an output of the cable leakage receiver.
 13. Amicro-response unit to be connected to a tap in a cable televisioncommunication system providing cable signals to a user, comprising:atransmitter for generating and wirelessly transmitting a first signalindicating a status of the tap; a receiver for wirelessly receiving asecond signal; a controller for controlling an operation of the tapbased on the received second signals; wherein the controller comprises acable leakage receiver for detecting a radiation leakage of the cablesignals, and for generating the first signal in response to an output ofthe cable leakage receiver.